1. Field of the Invention
The invention relates to a hanger for suspending a liner in a cased subterranean well, and particularly to a hydraulically actuated liner hanger.
2. Background of the Invention
Liner hangers have long been utilized in cased wells to suspend a liner extending from approximately the end of the casing to the bottom of the particular well. Such liners are suspended from the casing by a plurality of peripherally spaced slips which are forced into biting engagement with the internal wall of the casing by axial movement relative to ramps provided on the exterior of the tubular body of the liner hanger. Such relative movement has, in the past, been provided by hydraulic means actuated by pressured fluid supplied from the well surface.
All of the prior art hydraulically actuated liner hangers have required that one or more radial ports be provided in the liner hanger to transmit fluid pressure to an actuating piston disposed on the exterior of the liner hanger. Thus, when the hanger is set, seals must be provided in straddling relationship to the radial ports to prevent well fluids from flowing through such ports from the bore of the suspended liner into the well annulus surrounding the liner. Such seals are exposed to well fluids and are subject to rapid deterioration due not only to the corrosive effects of well fluids, but also due to recurrent axial stresses imposed on the seals by movements of well fluids in an upward direction and movement of treatment fluids in a downward direction.
It is therefore highly desirable that a hydraulically actuated line hanger be provided which does not result in radial ports extending through the body of the liner hanger. There is the further problem with prior art hydraulically actuated liner hangers in that the fluid utilized to effect the hydraulic setting of the hanger is readily contaminated by well fluids. The adverse effects of trash and corrosive elements of well fluids on hydraulically operated mechanism is well known to those skilled in the art.